I've been using the HRM for training so far and I want to get more details/serious on my training.And I want to get a powermeter. I've been looking at power2max since I could get them around 2k or under.My question is should I get a powertap( since its cheaper) or power2max or save up a bit more to get a SRM??Any thoughts would be appreciated..Thanks

I've been training on power for a while, so I can offer a few points to consider:

1. How many bikes do you have and what is the point of your training? If you've got more than one bike you may want to consider a powertap for ease of switching between bikes so you can always train with power (to track training loads etc). If you're road / criterium racing then a powermeter is not as important to race with as for a time trial (where you may TT to a set power schedule), moreso for diagnostics after the race. Powertaps have nothing but great reviews for a reason, and you can pick up a rear wheel only on a site like wiggle for ~$850.

2. You can pick up an FSA Gossamer power2max (Crank + spider) for under AUD1000 from bikecycle.co.nz. You'll just need to purchase the rings, and maybe a BB (depending on what you're already running) and you'll be on your way. If you want a slightly nicer crank, they have other options for slightly more (e.g. Rotor, SRAM, BOR)

3. Quarq really has taken over as the gold standard for power meters (in my opinion). They now have a high accuracy than SRM (+/- 1.5% with left/right balance), and battery changing does not require you to send it back to the factory for re-calibration. They are also significantly cheaper than SRM - Competitive cyclist (http://www.competitivecyclist.com) have the FSA SL-K Light Quarq Cinqo for ~USD1400 (Crank, spider, rings..everything), and Rotor offerings for not much more....

4. The new Rotor crank arm based (not spider) power meter looks quite impressive...this will offer true left/right balance and the pricing seems to be on par with Quarq

As a very happy Power2Max user I can say the series 2 units with the improved temp sensor are fantastic. The series 3 versions will also do L/R but I have never seen much point in this.

Couple of thinks to consider in your decision.

SRM are expensive and require to be sent back to the local distributor every 18-24 months for battery replacement. All the other this is a do it yourself process.

Powertap are the cheapest, not by much, but restricted you to a single wheeler. I can swap my cranks over in about 5 minutes.

The Quarq units have had some problem in the early units with moisture shorting units out. They also require that the ring bolts be tightened to a specific torque and have a 5-6 hour bed in every time y out touch them where the accuracy is suspect.

Power2Max have had reported problems with accuracy due to temp drift. I have had both a series 1 and 2 units and can not seen this in a single instance.

Bike co nz is the Australia distributor and are fantastic to deal with

I've been training on power for a while, so I can offer a few points to consider:

1. How many bikes do you have and what is the point of your training? If you've got more than one bike you may want to consider a powertap for ease of switching between bikes so you can always train with power (to track training loads etc). If you're road / criterium racing then a powermeter is not as important to race with as for a time trial (where you may TT to a set power schedule), moreso for diagnostics after the race. Powertaps have nothing but great reviews for a reason, and you can pick up a rear wheel only on a site like wiggle for ~$850.

2. You can pick up an FSA Gossamer power2max (Crank + spider) for under AUD1000 from bikecycle.co.nz. You'll just need to purchase the rings, and maybe a BB (depending on what you're already running) and you'll be on your way. If you want a slightly nicer crank, they have other options for slightly more (e.g. Rotor, SRAM, BOR)

3. Quarq really has taken over as the gold standard for power meters (in my opinion). They now have a high accuracy than SRM (+/- 1.5% with left/right balance), and battery changing does not require you to send it back to the factory for re-calibration. They are also significantly cheaper than SRM - Competitive cyclist (http://www.competitivecyclist.com) have the FSA SL-K Light Quarq Cinqo for ~USD1400 (Crank, spider, rings..everything), and Rotor offerings for not much more....

4. The new Rotor crank arm based (not spider) power meter looks quite impressive...this will offer true left/right balance and the pricing seems to be on par with Quarq

Hope that helps

1. Powertaps are good, used them for many years. Select your model carefully, some are definitely better/more reliable than others. A Powertap typically won't last nearly as long as crank based meter though.

3. Quarqs, IME, are no more accurate than SRM, and tend to experience a little more zero offset drift than SRMs typically do. They are also more sensitive to slope calibration variance with changes of chainrings. Keep in mind that if you do need to adjust a Quarq's calibration, it will require additional hardware (such as a wahoo ANT+ USB dongle and an iPhone). I'd certainly recommend the newer SRAM Red model over the earlier models. SRM slope calibration is user adjustable with no additional hardware. Quarq's user replaceable battery is good. New SRM batteries are now rated to 1900 hours of use.

For any US retail price on Quarq, remember to adjust for the (real) exchange rate and add GST and shipping costs.SRM's FSA Gossamer is available for $2,109, delivered in Australia.

4. No crank based power meter can offer true left-right balance since the cranks are a connected system. IOW it's possible to have the same L-R numbers with an entirely different manner of pedal force application. L-R balance is a gimmick IMO but if you really want the detailed data, then SRM's torque sample rate (200Hz) is far superior than most of the other power meters (Powertap & Quarq: 60Hz, P2M: 50Hz, although the new Rotor samples at 500Hz) and it is the only meter that provides access to the raw torque data - but it requires additional specialist hardware/software. This is not something regular power meter users need concern themselves with.

I just bought fulcrum zeros I guess powertap is out of the equation Atm SRM is my first choice, And does anyone have any problem with power2max readings? I've read a few stories about temp changes on power2max.And for SRM, how easy is it to switch between bikes?

ririz wrote:I just bought fulcrum zeros I guess powertap is out of the equation Atm SRM is my first choice, And does anyone have any problem with power2max readings? I've read a few stories about temp changes on power2max.And for SRM, how easy is it to switch between bikes?

SRM, Quarq, P2M power meters are all crank sets and the difficulty or ease of removing and swapping to another bike is no more or less than for the equivalent crank without a power meter. You just need to make sure that the bottom brackets on each bike are compatible.

The only difference for the Quarq and SRM is the requirement for a cadence magnet to be fitted (you can get a spare to fit to 2nd bike).

Some are very easy to remove/replace, as shown in this example video by Tom Anhalt:

jcjordan wrote:I have a P2M and have only managed to come close to gettingbthe drift that a number of people have mentioned.

To do this I had to set my trainer up in a cold shed and then do 30 min on a turbo without allowing it to calibrate. Screw the the reading by around 10 watts.

The newer versions have an better temp sensor to help manage this better.

Also if you want to swap your rings the P2M does not require recalibration like the Quarq, handy if you want to go for a bigger ring in TT.

As Alex/RST has pointed out SRM is the best on the market but you pay a premium for it.

I'd be really surprised if a P2M didn't require recalibration. That's a very bold claim to make.

All power meters need an ability to validate calibration. IMO, they should all provide the ability to update that calibration, but only SRM & Quarq enable that (with Quarq requiring additional hardware to do it).

jcjordan wrote:The P2M lack of need to recalibrate was one of the reasons that I decided to go for them over Quarq.

Have gone between a 56 and 53 round rings with no problem and now on Q rings

That tells me straight away something's not right. Q-rings will by their very nature change the accuracy of a crank based power meter because they are designed to alter one of the fundamental assumptions power meters use when calculating power.

Did you do calibration checks when changing rings? Some units this doesn't affect them, others seem more sensitive to the change and type of ring used.

In terms of swapping a quarq between bikes, it takes about the same time and mucking around as swapping a rear wheel with a power tap. Takes one bolt, and about 2 mins to swap cranks... Assuming BB is compatible on the bike it's being swapped to....

I've used both hub and crank based systems a bit, the decision really comes down to personal preference. As mentioned before, if you have different wheels you want to swap onto bike, the crank based system is the go. Swapping this between bikes is pretty easy as well, depending on the bottom bracket system used. Powertaps have, IMO, been pretty solid and reliable. I find chucking the rear wheel between bikes less of a hassle (though only marginally) then swapping cranks. They are also cheaper.

jcjordan wrote:The P2M lack of need to recalibrate was one of the reasons that I decided to go for them over Quarq.

Have gone between a 56 and 53 round rings with no problem and now on Q rings

That tells me straight away something's not right. Q-rings will by their very nature change the accuracy of a crank based power meter because they are designed to alter one of the fundamental assumptions power meters use when calculating power.

Did you do calibration checks when changing rings? Some units this doesn't affect them, others seem more sensitive to the change and type of ring used.

According to P2M chaining swaps and the use of oval shape will not effect the readings.

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